Touch Sensor Pad with Composite Metal Layer for Low Resistance Bonding
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Solution Overview
Problem
The challenge is to ensure a reliable electrical connection between a touch pad and a flexible printed circuit pad in display devices, particularly as the touch pad becomes smaller, leading to potential defects and increased resistance.
Innovation Solution
A touch sensor design that includes a conductive bonding member, such as a metal material, bonded between the touch pad and the flexible printed circuit pad, using a fusion bonding or ultrasonic wave bonding method to enhance adherence and reduce resistance, with a transparent metal oxide first layer and a metal second layer configuration to facilitate proper curing and connection.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Volume of moving object
If the touch pad becomes smaller to reduce device thickness and bezel size, then the device profile is improved, but the electrical connection reliability between touch pad and flexible printed circuit pad deteriorates
Solution Approach 1:
The touch pad is constructed as a composite structure with a first touch pad layer made of transparent metal oxide and a second touch pad layer made of metal material. This composite structure enables both small size and reliable electrical connection, as the metal layer provides excellent conductivity while the transparent metal oxide layer maintains touch sensitivity and optical properties.
Solution Approach 2:
A conductive bonding member is introduced as an intermediary component between the touch pad and flexible printed circuit pad. This bonding member ensures stable electrical connection even when the touch pad size is reduced, acting as a reliable connector that compensates for the challenges of miniaturization.
2Ease of manufacture
If conventional bonding methods are used for small touch pads, then the manufacturing process is simple, but the electrical connection stability deteriorates due to increased resistance
Solution Approach 1:
The invention changes the material parameters of the touch pad by introducing a metal layer with high electrical conductivity. This parameter change reduces resistance and improves electrical connection stability without complicating the manufacturing process, as the metal layer can be deposited using standard thin-film fabrication techniques.
3Device complexity
If a single-layer touch pad structure is used, then the manufacturing process is simple, but the electrical conductivity and connection reliability are insufficient
Solution Approach 1:
The touch pad employs a composite structure with a first layer of transparent metal oxide and a second layer of metal material. This composite design achieves high electrical conductivity and reliable connection while maintaining reasonable manufacturing complexity, as both layers can be formed using conventional thin-film deposition processes.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
This solution stabilizes the electrical connection, reduces resistance, and improves reliability by bonding the conductive member to both the touch pad and flexible printed circuit pad, addressing the issues of increased pressure on conductive balls in anisotropic conductive films and preventing resistance increases due to curing imperfections.
Implementation Method 1
using a fusion bonding or ultrasonic wave bonding method to enhance adherence and reduce resistance
Implementation Method 2
using a fusion bonding or ultrasonic wave bonding method to enhance adherence and reduce resistance
Data Source
AI summary
A touch sensor includes a touch sensing region, a touch sensing electrode in the touch sensing region, a touch extending wire extended to the touch sensing electrode, a touch pad on an end of the touch extending wire, a flexible printed circuit board overlapping the touch pad, a flexible printed circuit pad on the flexible printed circuit board and facing the touch pad, and a conductive bonding member between the touch pad and the flexible printed circuit pad. The conductive bonding member is bonded to each of the touch pad and the flexible printed circuit pad. The touch pad includes a first touch pad layer made of a transparent metal oxide, and a second touch pad layer on the first touch pad layer. The second touch pad layer is made of a metal material. The conductive bonding member is bonded to the second touch pad layer.